This proposal is for a study comparing 150 depressed and 150 nondepressed family practice 150 depressed psychiatric research patients. Patients will be selected on the basis of a self-report measure of depression and a structured diagnostic interview. The family practice patients will be drawn from local practitioners and the psychiatric patients will be from a university department of psychiatry depression unit. All patients will also receive a home interview assessing clinical, demographic, psychosocial, and physical health and health care variables. They will then receive follow-up interviews at 4.5 and 9 months. Additionally, family practice patients' physicians will complete brief ratings forms on them. The primary research aim is to evaluate the appropriateness of generalization from the psychiatric literature to primary medical care by examining qualitative and quantitative differences among depressed and nondepressed family practice patients and depressed psychiatric patients, as well as to identify important homogeneous subgroups of depressed family practice patients. Additionally, the proposed research seeks to determine predictors of detection of depression by family physicians and the outcome of depression among family practice and psychiatric patients at 4.5 and 9 months. Unrecognized and untreated depression is a major public health problem. Most persons suffering from clinically significant depression do not receive treatment, and the majority of those in treatment receive it in primary care rather than specially mental health settings. Yet, current knowledge and treatment recommendations are based mainly on research with tertiary psychiatric populations. The challenges facing primary care physicians attempting to detect and diagnose depression in their practices and make appropriate treatment decisions may be quite different than for professionals in other contexts. Results of the proposed research will be important in defining this challenge, and they will have immediate practical implications for efforts to improve the detection, diagnosis, and treatment of depression in primary care.